Co-encapsulation of fish oil and carotenoids with different wall materials using a mono-disperse spray dryer

Abstract

Fish oil and carotenoids can provide many health benefits for human, such as vision protection, reducing the risk of heart disease and preventing cancer. However, fish oil and carotenoids are prone to oxidation. This research was conducted to develop a stable system to deliver these bio-actives into functional foods by co-encapsulating them in the same system. Spray drying microencapsulation is a method used for delivery of functional ingredient to food, which converts liquid phase to the relatively stable solid microcapsules. Co-encapsulation of fish oil and carotenoids (β-carotene and lutein) were achieved by producing oil-in-water emulsions by a microfluidizer using gum arabic (GA) and octenyl succinic anhydride (OSA)-modified starch as emulsifiers, with different wall to core ratios. A mono-dispersed spray dryer was used to produce stable microcapsules. Properties including droplet size, polydispersity index, density, flowability, moisture content, water activity, glass transition temperature (Tg), encapsulation efficiency and morphology of the powder produced were investigated. Storage trial of selected samples was carried out under 25°C and 55°C for 50 days to further test stability, using parameters including color, water activity and retention of carotenoids and fish oil. One powder sample with GA and OSA starch mixture as wall material (at wall to core ratio 4:1), was also prepared using freeze-drying method to provide comparison to the spray dried samples. The results showed OSA starch was a better wall material than GA. Samples that contained OSA starch had smaller droplet size and more uniform distribution in both emulsion and powder forms. These samples also had better flowability, lower moisture content, higher encapsulation efficiency, higher Tg and no damages on the surface. OSA has been proven to give a good protection against oxidation and other deteriorative reactions. This was further verified during storage, as samples containing OSA had better retention of both fish oil and carotenoids. In addition, a higher wall to core ratio provided better protection of the core phase with the same wall composition. Furthermore, it was proven that freeze drying method was not suitable for co-encapsulating of fish oil and carotenoids, as the microcapsules' structures were damaged resulting in poor stability. In summary, the present study has shown co-encapsulation of fish oil and carotenoids could be potentially implemented using emulsion method coupled with mono-disperse spray drying, which could be further used as a functional delivery system.